The British Journal of Sports Medicine published a systematic review* last year on whether schoolbag use is a risk factor for back pain in children and adolescents. This is often cited as a cause of back pain in children but the findings of the research may come as a surprise.
They found that there is no convincing evidence that aspects of schoolbag use increase the risk of back pain in children and adolescents.
The article is free to read on BJSM here https://bjsm.bmj.com/content/52/19/1241
*A systematic review – is basically a summary of the results of available carefully designed healthcare research studies (controlled trials) which provides a high level of evidence on the effectiveness of healthcare interventions